diff --git a/src/buffer/katetextline.h b/src/buffer/katetextline.h
--- a/src/buffer/katetextline.h
+++ b/src/buffer/katetextline.h
@@ -414,13 +414,13 @@
      */
     short attribute(int pos) const
     {
-        for (int i = 0; i < m_attributesList.size(); ++i) {
-            if (pos >= m_attributesList[i].offset && pos < (m_attributesList[i].offset + m_attributesList[i].length)) {
-                return m_attributesList[i].attributeValue;
-            }
-
-            if (pos < m_attributesList[i].offset) {
-                break;
+        // find the lowest item that has offset >= pos in a binary search
+        auto first = std::lower_bound(m_attributesList.cbegin(), m_attributesList.cend(),
+                                      pos, [](const Attribute &x, const Attribute &y)
+                                              {return x.offset < y.offset;} );
+        if (first != m_attributesList.cend()) {
+            if (pos < ((*first).offset + (*first).length)) {
+                return (*first).attributeValue;
             }
         }